MAINTAINERS: add "B:" for URI where to file bugs

MAINTAINERS: add "B:" for URI where to file bugs

Different subsystems and drivers have different preferences for where to
file bugs and what information to include.  Add "B:" entry for
specifying the URI for the bug tracker directly, a web page for detailed
info on filing bugs, or a mailto: URI.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jani Nikula <[email protected]>
Reviewed-by: Andrew Donnellan <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Cc: Joe Perches <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>